3GPP LTE (3rd generation partnership project long term evolution: hereinafter abbreviated ‘LTE’) and LTE-advanced (hereinafter abbreviated ‘LTE-A’) communication systems are schematically explained as an example of a mobile communication system to which the present invention is applicable.
FIG. 1 is a schematic diagram of E-UMTS network structure as one example of a wireless communication system. E-UMTS (evolved universal mobile telecommunications system) is a system evolved from a conventional UMTS (universal mobile telecommunications system). Currently, basic standardization works for the E-UMTS are in progress by 3GPP. E-UMTS is called LTE system in general. Detailed contents for the technical specifications of UMTS and E-UMTS refers to release 8 and release 9 of “3rd generation partnership project; technical specification group radio access network”, respectively.
Referring to FIG. 1, E-UMTS includes a user equipment (UE), a base station (BS, eNode B, or eNB), and an access gateway (hereinafter abbreviated AG) connected to an external network in a manner of being situated at the end of a network (E-UTRAN). The base station may be able to simultaneously transmit multi data streams for a broadcast service, a multicast service and/or a unicast service.
One base station contains at least one cell. The cell provides a downlink transmission service or an uplink transmission service to a plurality of user equipments by being set to one of 1.25 MHz, 2.5 MHz, 5 MHz, 10 MHz, 15 MHz, and 20 MHz of bandwidths. Different cells can be configured to provide corresponding bandwidths, respectively. A base station controls data transmissions/receptions to/from a plurality of the user equipments. For a downlink (hereinafter abbreviated DL) data, the base station informs a corresponding user equipment of time/frequency region on which data is transmitted, coding, data size, HARQ (hybrid automatic repeat and request) related information and the like by transmitting DL scheduling information. And, for an uplink (hereinafter abbreviated UL) data, the base station informs a corresponding user equipment of time/frequency region usable by the corresponding user equipment, coding, data size, HARQ-related information and the like by transmitting UL scheduling information to the corresponding user equipment. Interfaces for user-traffic transmission or control traffic transmission may be used between base stations. A core network (CN) consists of an AG (access gateway) and a network node for user registration of a user equipment and the like. The AG manages a mobility of the user equipment by a unit of TA (tracking area) consisting of a plurality of cells.
Wireless communication technologies have been developed up to LTE based on a wideband code division multiple access (WCDMA). Yet, the ongoing demands and expectations of users and service providers are consistently increasing. Moreover, since different kinds of radio access technologies are continuously developed, a new technological evolution is required to have a future competitiveness. Cost reduction per bit, service availability increase, flexible frequency band use, simple structure/open interface and reasonable power consumption of user equipment and the like are required for the future competitiveness.
Recently, ongoing standardization of the next technology of LTE is performed by 3GPP. Such technology shall be named LTE-A in the present specification. Big differences between LTE system and LTE-A system may include a system bandwidth difference and an adoption of a relay node.
The goal of LTE-A system is to support maximum 100 MHz wideband. To this end, LTE-A system uses carrier aggregation or bandwidth aggregation to achieve the wideband using a plurality of frequency blocks.
According to the carrier aggregation, a plurality of frequency blocks are used as one wide logical frequency band to use wider frequency band. And, a bandwidth of each frequency block may be defined based on a bandwidth of a system block used by LTE system. And, each frequency block is transmitted using a component carrier.
Although the carrier aggregation technology is adopted by the LTE-A system, which is a next generation communication system, a conventional technology is unable to support an UL power control operation of a user equipment in a multi-carrier system. In particular, it has never been studied yet on a method of reporting a PHR (power head room) for a multi-carrier, a PHR configuration method for PHR transmission, a format, and the like.